What is Use your Illusion

Use your Illusion is a novel mechanism for user authentication that is secure and usable regardless of the size of the device on which it is used. The system relies on the human ability to recognize a degraded version of a previously seen image.

Online Demo

You can try Use Your Illusion on your browser. Please enable JavaScript and to accept cookies when trying Use Your Illusion. Note: We do not collect any personal information on this website; cookies are only used to track your progress in the authentication process.
Try it now!


To better understand the cognitive process behing Use Your Illusion, try the following experiment.

  1. The above image is a distortion of a photo. Try to guess what the original photo represents.
  2. Click the image, the original photo pops up. Compare your guess to the original photo.
  3. Look again at the distorted image. Do you see what it looks like now?
To someone who has seen both pictures, it is clear that the distorted image represents the object in its original image, and that seeing the distorted image evokes the original object. However, without having been exposed to the original photo, the distorted image does not carry much meaning.

More details? Check our papers

Eiji Hayashi, Nicolas Christin, Rachna Dhamija, and Adrian Perrig
Use Your Illusion: Secure Authentication Usable Anywhere
In Proceedings of the Fourth Symposium on Usable Privacy and Security (SOUPS'08). Pittsburgh, PA. July 2008
[paper] [slides]
See also preliminary version:
Mental Trapdoors for User Authentication on Small Mobile Devices
CMU CyLab Technical Report CMU-CyLab-07-011, August 2007